Construction methods for backside illuminated image sensors

Abstract

A method of constructing a backside illuminated image sensor is described. The method includes the steps of forming a semiconductor wafer, forming at least electrical contacts in the semiconductor wafer, forming, in a handle wafer separate from the semiconductor wafer, a plurality of via holes, attaching the semiconductor wafer to the handle wafer such that the via holes in the handle wafer are aligned with the respective electrical contacts on the semiconductor wafer, removing the substrate layer from the semiconductor wafer, removing at least a portion of the handle wafer to expose the plurality of via holes, filling each of the exposed via holes with a conductive material and applying a solder material to each of the exposed via holes such that the conductive material in each of the via holes is electrically connected to the solder material.

Description

BACKGROUND OF THE INVENTION[0001]The present invention relates to construction methods for backside illuminated image sensors and, more particularly, to construction methods for backside illuminated image sensors using improved methods for providing mechanical integrity for the semiconductor wafer during processing and performing high temperature processing out of the presence of color filters.[0002]Solid state image sensors, including complimentary metal oxide semiconductor (CMOS) imagers and charge-coupled devices (CCD), may be used in many different digital imaging applications to capture scenes. A solid state image sensor may include an array of pixels arranged on a semiconductor wafer. Pixel arrays may be formed on semiconductor wafers using semiconductor processing techniques such as, for example, photolithography, ion implantation, oxidation, thin film deposition and etching. When exposed to incident light to capture a scene, a photosensitive element of each pixel in the arra...

AI Technical Summary

Problems solved by technology

Some amount of incident light may be lost due to absorption and reflection of incident light in the interconnect structures.

Additionally, some amount of light intended for a given pixel may end up in neighboring pixels due to diffraction and reflection, creating undesirable optical crosstalk between the pixels.

Microlenses, however, may not sufficiently reduce the light loss and optical crosstalk and may be complex to design and manufacture.

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